
Following the likes of Joe Sandz and Emma Lillie Lees, Rosanna Smith will be making the cross from No Place Like Holmes to The Mary Morstan Mysteries in order to play an ancestor.
Rosanna originally appeared as the no nonsense librarian Miss Katrina Bliss in the episode "Dawn Of The Red".
Her appearance in the NPLH spin off will be as trainee convent nun Sister Abigail Bliss.
The episode, the 4th of the 2nd series, is expected to be released in November.